Fluid passages in vehicles (e.g., aircraft, automobiles, boats, etc.) may, over time, accumulate impurities from the fluid flowing through such fluid passages. The impurities may cause blockages in the fluid passages. As a result, there may be a pressure differential between the fluid flow into the fluid passage (inlet flow) and the fluid flow out the fluid passage (outlet flow). Because of the blockage in the fluid passage, the inlet flow may have a higher pressure than the outlet flow. If the inlet flow reaches a certain pressure threshold, a bypass valve may open to allow some of the inlet flow through the bypass valve to reduce the pressure. The bypass valve opening may indicate that the fluid passage (such as a filter or heat exchanger) may need to be replaced because there is significant buildup of impurities in the fluid passage.